Docs: How to understand JGrass's console engine - part IV, how to use it without JGrass?

I really want to drop a note for developers interested in this.

Alright, The JGrass console engine can be used without JGrass. All you need are the two console plugins from the JGrass package:

• eu.hydrologis.jgrass.console
• eu.hydrologis.jgrass.console.editor

At that point lets code:

              /*
               * prepare to use the console environment
               */
              PipedOutputStream out = new PipedOutputStream();
              PrintStream pStream = new PrintStream(out);
              JGrass console = ConsolePlugin.console();
              if (null == console) {
                              // throw something
              }

Set some options to the engine:

              ProjectOptions projectOptions = new ProjectOptions(pStream, pStream, pStream);
              PreferencesInitializer.initializeStartupProjectOptions(projectOptions);
              projectOptions.setOption(ProjectOptions.COMMON_GRASS_DATABASE, new File(
                      locationPath).getParent());
              projectOptions.setOption(ProjectOptions.COMMON_GRASS_LOCATION, new File(
                      locationPath).getName());
              projectOptions.setOption(ProjectOptions.COMMON_GRASS_MAPSET, mapsetName);
              projectOptions.setOption(ProjectOptions.CONSOLE_COMPILE_ONLY, new Boolean(false));
              projectOptions.setOption(ProjectOptions.CONSOLE_ASYNC_MODE, new Boolean(false));
              URL rtUrl = Platform.getBundle(ConsolePlugin.PLUGIN_ID).getResource("rt"); //$NON-NLS-1$
              String rtPath = null;
              try {
                  rtPath = FileLocator.toFileURL(rtUrl).getPath();
              } catch (IOException e) {
                  HydrocarePlugin.log("HydrocarePlugin problem", e);  //$NON-NLS-1$
                  e.printStackTrace();
                  return;
              }
              projectOptions.setOption(ProjectOptions.CONSOLE_DIRECTORY_INCLUDE,
                      new String[]{rtPath});

Note that the FileLocator.toFileURL stuff is needed only if inside an RCP application.

Now create the command you want to execute:

              String command = "g.region -p";

And execute it!

              console.dispatch(projectOptions, command);

UPDATE
_________


I just created a class to use the console in standalone mode:

/**
 * Standalone console engine
 * 
 * @author Andrea Antonello - www.hydrologis.com
 */
public class JGrassConsole {
    private final String grassDbPath;

    private final String locationName;

    private final String mapsetName;

    private final String rtPath;

    private boolean doDebug = false;

    private String gisbase = "/"; //$NON-NLS-1$

    public JGrassConsole(String grassDbPath, String locationName,
            String mapsetName, String rtPath, String cmd, boolean debug,
            String grass) {
        this.grassDbPath = grassDbPath;
        this.locationName = locationName;
        this.mapsetName = mapsetName;
        this.rtPath = rtPath;
        this.doDebug = debug;
        if (grass != null) {
            gisbase = grass;
        }
        /*
         * prepare to use the console environment
         */
        PrintStream outStream = new PrintStream(System.out);
        PrintStream errStream = new PrintStream(System.err);
        JGrass console = (JGrass) new ConsoleEngine();
        if (null == console) {
            // throw something
        }

        ProjectOptions projectOptions = new ProjectOptions(outStream,
                outStream, errStream);

        initialize(projectOptions);

        console.dispatch(projectOptions, cmd);
    }

    /**
     * @param args
     */
    @SuppressWarnings("nls")
    public static void main(String[] args) {

        String grassDbPath = null;
        String locationName = null;
        String mapsetName = null;
        String rtPath = null;
        String cmd = null;
        String grass = null;
        boolean debug = false;

        for (String arg : args) {
            System.out.println(arg);
            if (arg.startsWith("-db")) {
                grassDbPath = arg.split("=")[1];
            }
            if (arg.startsWith("-loc")) {
                locationName = arg.split("=")[1];
            }
            if (arg.startsWith("-maps")) {
                mapsetName = arg.split("=")[1];
            }
            if (arg.startsWith("-rt")) {
                rtPath = arg.split("=")[1];
            }
            if (arg.startsWith("-cmd")) {
                cmd = arg.split("=")[1];
            }
            if (arg.startsWith("-deb")) {
                debug = true;
            }
            if (arg.startsWith("-grass")) {
                grass = arg.split("=")[1];
            }
        }

        if (grassDbPath == null || locationName == null || mapsetName == null
                || rtPath == null || cmd == null) {
            System.out
                    .println("USAGE: -db= -loc= -maps= -rt= -cmd= [-grass=] [-debug]");
            System.exit(1);
        }

        new JGrassConsole(grassDbPath, locationName, mapsetName, rtPath, cmd,
                debug, grass);

    }

    public void initialize(ProjectOptions options) {
        options.setOption(ProjectOptions.CONSOLE_ASYNC_MODE, false);
        options.setOption(ProjectOptions.CONSOLE_THREAD_RESTRICTION, 0);
        options.setOption(ProjectOptions.CONSOLE_COMPILE_ONLY, false);

        // Logging Level: DEBUG
        options.setOption(ProjectOptions.CONSOLE_LOGGING_LEVEL_DEBUG, doDebug);
        // Logging Level: TRACE
        options.setOption(ProjectOptions.CONSOLE_LOGGING_LEVEL_TRACE, doDebug);
        // Include directory; RTTI - runtime type informations - the
        // reserved
        // words...
        options.setOption(ProjectOptions.CONSOLE_DIRECTORY_INCLUDE,
                new String[] { rtPath });

        // Source directory; default script file location...
        options.setOption(ProjectOptions.CONSOLE_DIRECTORY_SOURCE, null);

        // User information - the home directory of the current user...
        options.setOption(ProjectOptions.NATIVE_MODEL_USER_HOME, System
                .getProperty("user.home")); //$NON-NLS-1$

        // User information - the user name of the current user...
        options.setOption(ProjectOptions.NATIVE_MODEL_USER_NAME, System
                .getProperty("user.name")); //$NON-NLS-1$

        // Debug mode...
        options.setOption(ProjectOptions.NATIVE_MODEL_DEBUG, doDebug);

        // Installation folder of GRASS...
        options.setOption(ProjectOptions.NATIVE_MODEL_GISBASE, gisbase);

        // GRASS database, location, mapset path...
        options.setOption(ProjectOptions.COMMON_GRASS_MAPSET, grassDbPath
                + File.separator + locationName + File.separator + mapsetName
                + File.separator);

        options.setOption(ProjectOptions.JAVA_MODEL_TIME_DELTA, null);
        options.setOption(ProjectOptions.JAVA_MODEL_TIME_ENDING_UP, null);
        options.setOption(ProjectOptions.JAVA_MODEL_TIME_START_UP, null);
    }

}